Conventionally, as a method of increasing/converting the frequency of an input wave in an electromagnetic wave region of a frequency of 1 THz or less, there has been used a method in which electric nonlinearity of a semiconductor element such as a varactor diode or various transistors is used, and the element is incorporated in a resonator to perform multiplication (see non-patent documents 1 and 2).
Besides, conventionally, non-patent document 3 discloses a theoretical analysis of reflected and transmitted waves in the case where the boundary surface of a stationary plasma moves at high speed. Non-patent document 4 discloses a theoretical analysis of reflected and transmitted waves in the case where only the boundary surface of a stationary dielectric moves at high speed. Non-patent document 5 discloses the Doppler frequency transition of an electromagnetic field moving at high speed to generate a frequency change by the Doppler effect, in which a variable-capacitance diode is mounted to a coaxial cable, a voltage pulse is made to travel to generate an equivalent moving boundary surface, and a change in transmission frequency of an incident wave is measured. Non-patent document 6 discloses an experiment to examine that in a line loaded with a capacitor charged at high voltage, discharge is performed by a laser beam as a trigger to generate an equivalent plasma boundary surface, and the electromagnetic wave generated at that time is in the microwave band.
Non-Patent Document 1
E. Schlecht, G. Chattopadhyay, A. Maestrini, A. Fung, S. Martin, D. Pukala, J. Burston and I. Mehdi, “200, 400 and 800 GHz Schottky Diode “Substrateless” Multipliers: Design and Results” 2001 MMT-S International Microwave Symposium Digest, vol. 3, pp. 1649-1652, 2001.
Non-Patent Document 2
X. Melique, A. Maestrini, R. Farre, P. Mounaix, M. Favreau, O. Vanbesien, J-M. Goutoule, F. Mollot, G. Beaudin, T. Narhi, D. Lippens, “Fabrication and Performance of InP-based Heterostructure Barrier Varactors in a 250-GHz Waveguide Tripler” Microwave Theory and Techniques, IEEE Transactions on, vol. 48, no. 6, pp. 1000-1006, June 2000.
Non-Patent Document 3
M. Lampe, et al., “Submillimeter-Wave Production by Upshifted Reflection from a Moving Ionization Front”, Year 1977
Non-Patent Document 4
C. S. Tsai and B. A. Auld, “Wave Interaction with Moving Boundaries”, 1967
Non-Patent Document 5
Hiroshi Ito, Kiyoshi Hayata, “Doppler Frequency Transition of Electromagnetic Field Moving at High Speed”, 1979
Non-Patent Document 6
J. R. Hoffman, et al., “High power radiation from ionization fronts in a static electric field in a waveguide”, 2001